State-Interaction Pair-Density Functional Theory Can Accurately Describe a Spiro Mixed Valence Compound

Sijia Dong, Kevin Benchen Huang, Laura Gagliardi, Donald G Truhlar

Research output: Contribution to journalArticle

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Abstract

Mixed-valence compounds with strong couplings between electronic states constitute one of the most challenging types of multireference systems for electronic structure theory. Previous work on a model mixed-valence compound, the 2,2′,6,6′-tetrahydro-4H,4′H-5,5′-spirobi[cyclopenta[c]pyrrole] cation, showed that multireference perturbation theory (MRPT) can give a physical energy surface for the mixed-valence compound only by going to the third order or by using a scheme involving averaging orbital energies in a way specific to mixed-valence systems. In this study, we show that second-order MRPT methods (CASPT2, MS-CASPT2, and XMS-CASPT2) can give good results by calculating the Fock operator for the zeroth-order Hamiltonian using the state-averaged density matrix. We also show that state-interaction pair-density functional theory (SI-PDFT) is free from the unphysical behavior of previously tested second-order MRPT methods for this prototype mixed-valence compound near the avoided crossing. This is very encouraging because of the much lower cost in applying SI-PDFT to large or complex systems.

Original languageEnglish (US)
Pages (from-to)2100-2106
Number of pages7
JournalJournal of Physical Chemistry A
Volume123
Issue number10
DOIs
StatePublished - Mar 14 2019

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Density functional theory
density functional theory
valence
Hamiltonians
Pyrroles
Electronic states
Interfacial energy
perturbation theory
Electronic structure
Cations
Mathematical operators
Large scale systems
interactions
Costs
pyrroles
complex systems
surface energy
prototypes
electronic structure
cations

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State-Interaction Pair-Density Functional Theory Can Accurately Describe a Spiro Mixed Valence Compound. / Dong, Sijia; Huang, Kevin Benchen; Gagliardi, Laura; Truhlar, Donald G.

In: Journal of Physical Chemistry A, Vol. 123, No. 10, 14.03.2019, p. 2100-2106.

Research output: Contribution to journalArticle

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